Medicament injection devices are utilised to administer a medicament to a user. Medicament injection devices have a needle for injecting the medicament. The needle is covered prior to medicament delivery to assure that the needle is clean during medicament delivery. The needle is furthermore preferably covered also after medicament delivery to ensure that the used needle does not unintentionally scratch or pierce the skin of a person handling the medicament injection device after usage. Moreover, it is also desirable that the needle obtains this protected position post medicament administration automatically without the involvement of a user, to render the medicament injection device difficult to reuse.
An example of a medicament injection device that provides needle protection after medicament delivery is disclosed in EP1090652 B1. This document discloses a needle guard assembly for the needle part of a syringe body in the form of a needle guard which is longitudinally displaceable along the syringe body, and with a grip plate being integrally formed on a part of the syringe body remote from the needle. The needle guard assembly includes a syringe body ending with a needle. A piston rod in the syringe body has a receiving part and a push-in part that telescopes into the receiving part. A syringe-body grip plate is integrally formed on the syringe body. The syringe-body grip plate opposes the needle. The needle guard covers the needle when the needle guard is displaced longitudinally.
The solution disclosed in EP1090652 B1 relies on the push-in part telescoping into the receiving part after a catch-mounting is broken by applying a pressure on the grip plate above a predetermined value after the medicament has been injected. If a user for example has a disease which severely limits the user's strength, preventing the user from breaking the catch/mounting, it may result in that the needle guard will not cover the needle after injection.